The present invention relates to a method for operating an internal combustion engine and a corresponding device.
A method for operating an internal combustion engine and a corresponding device is already conventional, in which combustion of a fuel in a fuel-air mixture introduced into the cylinder occurs in at least one cylinder. Moreover, adjusting devices, for example, an exhaust gas recirculation valve, a camshaft adjustment for the intake and/or the exhaust, variable valve timing or a charge movement valve are conventional, which influence the physical processes such as the exhaust gas recirculation rate, the intensity of movement of the fuel-air mixture, the volume of the fresh air supplied or the volume of the fuel-air mixture supplied, these physical processes modifying the distribution of the components and/or the total composition of the fuel-air mixture in the cylinder.
Furthermore, knock detection and knock control systems are conventional for internal combustion engines so if knock is detected in a cylinder, the ignition angle is retarded after the occurrence of a knock signal.
When the rate of the recirculated exhaust gas is increased, the base ignition angle is advanced by a fixed, specified angle in conventional internal combustion engines.
The method and device according to the present invention may provide the advantage that the internal combustion engine may be operated at the knock limit in dynamic operating states so that maximum efficiency is attained.
It may be advantageous to be able to bring the internal combustion engine rapidly to the knock limit when there is a change in the exhaust gas recirculation rate. This also applies to a change in the position of the charge movement valve or to a change in the air supply or the fuel-air mixture supply related to the camshaft adjustment or variable valve adjustment. An additional acceleration of the advance to the knock limit is attained if an advanced adjustment angle is added to the basic ignition angle. It may be further advantageous to reduce the adjustment angle for all cylinders simultaneously since it is thus possible to make the adaptation to the new conditions for all cylinders immediately. In certain cases when the individual characteristics of the individual cylinders are very different, it may be advantageous to reduce the adjustment angle rapidly cylinder-by-cylinder. It may be further advantageous to transmit the reference value rapidly when the adjustment angle is rapidly reduced since the knock detection should also be rapidly adapted to the new conditions. If knock or load dynamic occurs, it is then advisable to interrupt the rapid reduction to avoid knock.